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Sunday, October 21, 2007

A Good Light II

An anonymous commenter asks from where the school teacher got his evidence for a slowing speed of light. We can only guess! Perhaps he keeps up to date with news on Louise Riofrio's blog. Alternatively, he may have looked at wikipedia and observed that the 1926 experiment measured a value of 299796 km/sec, compared to the modern value of 299792.458 km/sec. This modern value is now the standard for $c$, which since 1983 has been used to define the metre.

Anyway, the lattes all worked well today and I'm enjoying a clear spring evening on this holiday weekend.

3 Comments:

The idea that light is slowing down is a favorite of "young earth creationists" who want the universe to be thousands of years old rather than billions of years old. They've been pushing the idea for years.

Despite appearances, this game has always been quite hopeless for the other side. It is impossible to prove that c is constant, because a more accurate measure could always prove you wrong. Better to join the winning side early!

The best one can do is establish a reference frame where c is constant, just like Earth is centre of the Universe. The truly self-centred also believe that everything revolves around them, but that is another story...